The earliest Cenozoic record of a horntail sawfly (Hymenoptera: Siricidae) in North America, from the Paleocene Paskapoo Formation, Canada

Journal article

A new horntail sawfly, Cenosirex speirsorum gen. et sp. nov. (Siricidae), is described from a single fossil specimen collected at the Munce’s Hill locality of the Paskapoo Formation in Alberta, Canada. The new genus is assigned to Siricinae sensu Rasnitsyn (1968) (= Siricinae + Tremicinae) based on the following combination of forewing characters: strongly corrugated wing membrane, moderately narrow ribbon-like costal space, presence of Sc, long 1-Rs with a reclival base, absence of 2rs-m, and basally positioned anal loop. The new taxon exhibits a mosaic of characters shared with several extinct and extant genera, but differs from them primarily in the absence of veins 1rs-m and 2rs-m in the forewing, and in having vein 1cu-a situated slightly distal to the midpoint of cell 1M. This discovery expands the known palaeoentomological diversity of the Paskapoo Formation, representing the first ‘Symphyta’ described from this Palaeocene unit. It also broadens the Palaeocene record of the Siricidae, previously documented only from Europe (France), to include North America, and highlights the need for further palaeontological investigation of the formation. We also provide new illustrations of the type material of Xeris muratensis Boderau et al., 2024, as the original figures were insufficient to clearly depict the diagnostic characters.

Authors: Jouault, C; Sasaguchi, K; Acorn, J; Sosiak, C

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Magnolia Press
• Journal: Palaeoentomology
• Volume: 9
• Issue: 3
• Pages: 243-253
• Publication date: 2026-06-29
• DOI: 10.11646/palaeoentomology.9.3.7
• EISSN: 2624-2834
• ISSN: 2624-2826
• Language: English
• Keywords: Alberta; fossil record; ‘Symphyta’; Siricoidea; taxonomy